Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

PA Systems A forum for discussion of all parts of a sound reinforcement or DJ system: loudspeakers, mixers (desks) etc.

12" or 15" tops, with 100Hz subs?  (live sound)
12" or 15" tops, with 100Hz subs?  (live sound)
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 18th April 2018, 07:07 PM   #21
Cableaddict is offline Cableaddict
diyAudio Member
 
Join Date: Nov 2016
Quote:
Originally Posted by chris661 View Post
You realise these dispersion angles happen over a couple of octaves at best, right?
Above 10kHz or so, you get beaming since the HF exit diameter is fairly large. Below a couple of kHz, most horns are too small to effectively control the dispersion.

Time to look at Synergy horns...

Chris

Yeah, I've read this recently, and good to know.

But I don't see how that changes things. Why else would manufacturers purposely control the vertical spread with "normal" horns? Even Tannoy has started doing this on the newest dual concentric designs.

Well, I dunno. Still on the fence. As I said before, those 90 conical T300's worked great, sounded incredible at the back of the room, so ......
  Reply With Quote
Old 18th April 2018, 07:49 PM   #22
Cableaddict is offline Cableaddict
diyAudio Member
 
Join Date: Nov 2016
BUT I WANT TO GET BACK THE THE ACTUAL THREAD TOPIC, FOR A MOMENT:

If anyone is still reading this, I have more thoughts about that "slightly anemic" sound my old system had in the low mids..

I've been thinking about 12's vs 15's again, AND -

I've been thinking about something Art Welter wrote, concerning PPSL and energy ABOVE 100 Hz. This has really puzzled me, but now I'm thinking about a speakers output passed the system crossover point. This is probably standard stuff for you guys, but new thinking for me. The first octave or two "on the other side" of the crossover is obviously important. (Slapping myself upside the head, with a loud "DUH," then seeing the lightbulb come on..... )

My old system was the T300's, with four sealed 18" Bag Ends. Crossed at 120 Hz.

The T300's are -3dB at 55Hz, with the dedicated processor.
OK, that seems about right, but the 12" cones in these coaxial speakers are more like 11", due to the large HF unit in the center. Could it be that the sub-crossover octave of 50 - 100 Hz doesn't carry well into the room?

OR: Could it be that the sealed 18's don't have enough energy above 120 Hz? (I know sealed cabinets have a natural high-end roll off.)
---------------------------------

If the above is correct, the solution would be to use corrective EQ, yes?
- But wouldn't it then be best to do this on only the tops, or on the subs?

With my new top speakers, (yet to be decided on, but most likely 12" mids ) I'll have to use my own electronics, probably likely a top-end DriveRack. The DriveRack will give me separate EQ control for both subs and tops (or all three drivers if I forgo any passive x-over) so I will then have the ability to do as above.

So - Is this the solution? Would pushing a little extra Eq at 80 Hz or so to the tops, while crossed over at 100 Hz, help the crossover point sound more substantial, or would I still have losses out in the room, or maybe even just be adding mud?

Is the answer simply more mid drivers (a dual 12", for instance) or - getting back to the main subject - using 15's instead of 12's?

Last edited by Cableaddict; 18th April 2018 at 07:53 PM.
  Reply With Quote
Old 18th April 2018, 07:54 PM   #23
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
12" or 15" tops, with 100Hz subs?  (live sound)
can a "lens" be of use sometimes with larger cones? - like recent JBL, "BBC" or oval ? - it can make things rougher

Click the image to open in full size.
  Reply With Quote
Old 18th April 2018, 09:36 PM   #24
SubSoniks is offline SubSoniks  Wales
diyAudio Member
 
Join Date: Nov 2005
Location: Wales
First port of call would be if you haven't already is to stick a mic in front of a stack, preferably 5m or more if possible from any boundaries and measure the response with REW, Holm, Arta or similar to see what is going on before binning the existing tops?
  Reply With Quote
Old 20th April 2018, 01:15 AM   #25
Cableaddict is offline Cableaddict
diyAudio Member
 
Join Date: Nov 2016
Quote:
Originally Posted by SubSoniks View Post
First port of call would be if you haven't already is to stick a mic in front of a stack, preferably 5m or more if possible from any boundaries and measure the response with REW, Holm, Arta or similar to see what is going on before binning the existing tops?
I did this toady, even though the HF is distorting a little. (Dues to the boxes being dropped,and the huge magnets shifting.)

I understand now at least a bit of what's happening.
I set up my old rig as it always was, with the stock 120Hz crossover for the tops, and not LPF for the sealed 18's.

At three feet, I can get pretty even from 38 - 18K, as expected. However, at even 30 feet away, there is a noticeable drop from maybe 100Hz to 300 or 400Hz. It hard to measure exactly as at that distance all sorts of weird stuff happens before it gets to the mic, but the change is significant.

So evidently I was right to worry about the coaxial 12's lack of cone area. Even a normal 12" surely does this at distance. Gotta' move as many air molecules as you can, just like with subwoofers.
----------------

I figured that I would have two solutons:

1: Go with 15's after all, despite the negatives you gusy have already mentioned.

2: Add a second (non coaxial) 12", as Tannoy is doing now with one of their VX speakers.

I spoke to Jeff at Radian today, and ran all this by him. (This guy appears to know his stuff. I'd love to get him and Art together, get 'em drunk & talking about speakers, and just sit back & record the whole thing. )

FWIW< here's what he told me:

Re 15's: Absolutely no good for me. Yes, there would be more cone area and thus better throw, but it has the beaming effect you guys talked about. He also mentioned their tests using their own Coaxials mounted on top of smallish subs, in order to simulate a typical "event D / "Bar Band" type of setup. No physical or electronic delay for the subs.

He said that the 15's required 30 feet to fully couple with the subs, whereas the 12's needed MUCH less distance. (He couldn't remember exactly. That's a big deal for me. I don't know if electronic delay would help with that or not, I didn't think to ask.
-------------------------

So we move on to the "two 12" mid drivers" thing, but he feels there would be too much phase smear. (Although a number of good companies have speakers liek this, including Fulcrum and Tannoy. OK, Tannoy is now Behringer, but, well, Fulcrum.)

His suggestion, which kinda' blew me back, is to run my subs at least an octave higher, since they have a lot more cone area. In fact, I will probably be using a total of six 12" , or possibly even twelve 10", in my new PPSL subs (unless I build small TH's) so that's a LOT of cone area, lots of high-mid capability, and not a lot of total cone movement so pretty reasonable modular distortion.

What bothers me about this is that I've always felt subs sound best when crossed at 120Hz or lower. The lower you go, the punchier they sound.
I still think so based on the stuff I have hear, but that a very limited sample.
Dennis thinks that with todays technology and super-strong neo magnets, subs can deal with higher frequencies and not lose any punch.

Kinda' sounds like what Art's been trying to get me to understand all this time. I think.
-----------------------------------

I am DYING to get some opinions on all this from you guys.
  Reply With Quote
Old 20th April 2018, 08:52 AM   #26
turk 182 is offline turk 182  Canada
diyAudio Member
 
Join Date: Oct 2012
can you give more specific details about your setup it seems as though there's an overlap in the frequency range between sub and mid high that is cancelling the low mid area. it could be a polarity issue or you may need a crossover with a steeper slope.
  Reply With Quote
Old 20th April 2018, 09:19 AM   #27
SubSoniks is offline SubSoniks  Wales
diyAudio Member
 
Join Date: Nov 2005
Location: Wales
Quote:
Originally Posted by turk 182 View Post
can you give more specific details about your setup it seems as though there's an overlap in the frequency range between sub and mid high that is cancelling the low mid area. it could be a polarity issue or you may need a crossover with a steeper slope.
+1 on that, reason I gave for measuring the system away from any boundaries is to see what the system is doing without the effect of the room, it will make it possible to set the xover between the lows and hi's much much more accurately, when yoy then take the system indoors you will be able to see what effect the room os having on the system. Where to place the mic is important.
Re the HF, have you dissasembled the HF drivers to check the diaphragms?
  Reply With Quote
Old 21st April 2018, 12:10 AM   #28
Cableaddict is offline Cableaddict
diyAudio Member
 
Join Date: Nov 2016
Quote:
Originally Posted by turk 182 View Post
can you give more specific details about your setup it seems as though there's an overlap in the frequency range between sub and mid high that is cancelling the low mid area. it could be a polarity issue or you may need a crossover with a steeper slope.
That's an interesting possibility, although if true it would probably be an ADDITIONAL issue as well.

But if it's a phase issue, wouldn't I hear that at all distances?

Both of my electronics (tops & subs) have phase switches, and I definitely tried both ways long ago, and preferred in-phase. - But I was only listening for the sound of the subs. I'll give this a try when I have time again to set it all up. (and the neighbors are all at work. )
  Reply With Quote

Reply


12&quot; or 15&quot; tops, with 100Hz subs?  (live sound)Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
2x 8" + 1,4" extreme tops upgrade Crashpc Multi-Way 16 17th December 2017 03:24 PM
Coming up! June 13th (Seattle), The 2nd Annual PNWAS "Live vs. Recorded" fork Clubs & Events 0 27th May 2013 07:49 AM
Dual 18" PA subs for live sound in club... hellonwheels PA Systems 31 22nd May 2013 06:44 PM
Blu Ray BD Disc "In Concert" resp "live at" - Overview wanted tiefbassuebertr Music 2 5th January 2012 02:54 PM
Cab "porting" help for live sound mains... tsnave Multi-Way 3 2nd August 2010 05:45 PM


New To Site? Need Help?

All times are GMT. The time now is 08:43 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki